Glassy molecularly dehydrated phosphates



Patented June 24, 1952 GLAS SY MOLECULARLY DEHYDRATED PHO SPHATES GeorgeB. Hatch, Allison Park, Pa., assignor, by mesne assignments, to Calgon,Incorporated, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.Application June 29, 1944, Serial No. 542,833

1 Claim. 1

This invention relates to glassy molecularly dehydrated phosphatesuseful for a variety of purposes. The present application is acontinuationin-part of my application Serial N 0. 505,605, filed October9, 1943, now Patent No. 2,539,305 issued January 23, 1951, which in turnis a continuationin-part of my application Serial No. 222,258, filedJuly 30, 1938, now abandoned. In those applications I have disclosed aprocess of inhibiting the precipitation of calcium carbonate in water byflowing the water in contact with very slowly water-soluble molecularlydehydrated phosphates. In the present application I claim certain veryslowly water-soluble molecularly dehydrated phosphates which aredisclosed but not claimed in the above referred to copendingapplications.

The glassy molecularly dehydrated phosphates herein claimed have variousapplications in addition to their function of stabilizing water againstthe precipitation of calcium carbonate as disclosed in my above referredto copending applications. They'may be employed to stabilizeiron-bearing waters so that red water and objectionable deposition ofhydrous ferric oxide may be obviated as disclosed in Rice Patent2,304,850. They may also be used advantageously in the process ofretarding the corrosion of metal by water as disclosed inRice and HatchPatent 2,337,856. The molecularly dehydrated phosphate glasses hereinclaimed may also be used to produce dispersion or defiocculation insuspensions of mineral matter, such as clays, pigments, fillers, andfinely divided metal oxides and salts in general. One specificapplication for which these phosphate glasses are particularly suited isthe control of the viscosity of the drillin muds.

Among the very slowly soluble molecularly dehydrated phosphate glasseswhich may be used according to the present invention, the following maybe mentioned:

1. The glassy molecularly dehydrated zinc phosphates, as for example,zinc metaphosphate glass or zinc tripolyphosphate glass.

2. The glassy molecularly dehydrated aluminum phosphates, as forexample, the glassy aluminum metaphosphate glass or aluminumtripolyphosphate glass.

3. Mixed molecularly dehydrated phosphate glasses of sodium and calcium,sodium and magnesium, or calcium and magnesium, as for example, themetaphosphate glasses or the tripolyphosphate glasses of sodium andcalcium, or sodium and magnesium, or calcium and magnesium.

Glassy zinc metaphosphate may be made by heating monobasic zincorthophosphate to dee hydrate it, then fusing it at 1000 C. and thenrapidly cooling it to prevent the formation of crystals. Glassy zincmetaphosphate may be made in other ways. For example, a starting mixturemay be prepared from zinc carbonate and orthophosphoric acid in theproportions of 1 mol of zinc carbonate to 2 mols of the acid. This Zinctripolyphosphate glass may be made in the same manner as zincmetaphosphate glass except that the proportions of zinc carbonate toorthophosphoric acid are in the molar proportions of 5 to 6, thereaction being represented by the following equation:

Aluminum metaphosphate glass or aluminum triployphosphate glass may bemade by mixing alumina and orthophosphoric acid in the proportionsrequired to form either the metaphosphate or the tripolyphosphate,heating the mixture to drive off the molecularly combinedwater at arelatively low temperature, preferably at about 600 C, then heating themass to fusion and quickly cooling it. It is much more diflic'ult toprepare glassy aluminum metaphosphate or aluminum tripolyphosphatebecause of the high temperature necessary to fuse it, which is in excessof 1500 C.

Equation 3 represents the formation of aluminum metaphosphate glass, andequation 4 the formation of aluminum triopolyphosphate glass.

(3) 1A1203+6H3PO4=A12033P205 glass+9H2O (4) 5Al203+18H3PO4= 5A12O3.9P2O5glass+ 27H2O A mixed calcium-sodium water-insoluble or very slowly watersoluble metaphosphate may be made by starting with a mixture of sodiumcarbonate, calcium carbonate, and orthophosphoric acid. The startingmaterials should be in the 3 ratio of 1 mol of total carbonate to 2 molsof orthophosphoric acid. The properties of the mixed metaphosphates maybe varied by controlling the ratio of sodium carbonate to calciumcarbonate. Thus, if a mixed metaphosphate glass with a rate of; solutiongreater than that of calcium metaphosphate but less than that of sodiummetaphosphate is desired, 1 mol of sodium carbonate and 1 mol of calciumcarbonate may be mixed with 4 mols of orthophosphoric acid and themixture dehydrated, fused and chilled, to give a glassy product with theapproximate molar composition of 1NazO.1CaO.2P2O5 The reaction isrepresented by equation 5.

The product consists analytically of 25 molar per cent Na20; 25 molarper cent 09.0; 59 molar per cent P205,

' It mixed calcium sodium 'waterdnsoluble or very slowly water-solubletripolyphosphate glass may be made in the same manner as the mixedcalcium-sodium metaphosphate glass except that the starting materialsare in amounts to supply a ratio of '5 mols of total metal oxide to 3mols of P205. It should be remembered that to produce 1 mol of P205 inthe final composition, 2 mols of orthophosphoric acid would be requiredin the initial mixture if orthophosphoric acid wereempl'oyed to supplythe P205 in the final products The formation of one of the many possiblesodium-calcium tripolyphosphate glasses ifi r sent b e uat 5- w .aNa eoeec osafiu oie 2Na20.30a0.3P205 glass+9H2O+5QO2 The product consistsanalytically of 25 molar per cent NazQ; 37% molar per cent CaO; 37 A;molar per cent P205.

M ed; m ne i -sodi m c l v d h drated phosphate glasses may be made withcompositions corresponding to the metaphosphate or the tripolyphosphateby starting with a mixture of sodium carbonate, magnesium carbonate andorthophosphoric acid in proper proportions as described for theproduction of calcium-sodium molecularly dehydrated phosphate glassesand proceeding in a similar manner.

Mixed molecularly dehydrated phosphate lasses Q cal i m a d a e m m y bea with compositions corresponding to the metaphosphate composition orthe tripolyphosphate c mpos t n y i in al iu b a e m 4 ployed in theproduction of the metaphosphate or tripolyphosphate glasses, the onlyrequirement being that in the production of metaphosphate glass thestarting materials be in the proportions of 1 mol of total metal oxideto 2 mols of phosphoric acid or 1 mol of P205, While in the case of thetripolyphosphate glasses the starting materials should be in the ratioof 5 mols of total metal oxide to 6 mols of phosphoric acid or 3 nesium.arbo a e d rhe h c acid n he 7 P 5 21 Proportions, heating the mixtureto drive off carbon dioxide and molecularly combined water at arelatively low temperature, preferably between 300 C. and 5001 CL, thenheating the mass to fusion which may require a temperature of 1000 C. orgreater, and chilling he fu o a isc ed i c e tion h the prq u tio qir nme p espha s T prqd qtiqn Qi o of th m n P b mixed calcium-magnesiummetaphosphate glasses is representedby equation 7, and the production ofone of the many possible mixed calcium-magnesium triopolyphosphate.glasses by equation 8.

2C aO.3M g0.3P-205 glass+9H20+5COz Any suitable starting materials maybe emmols of P205.

I have referred particularly in the preceding description to theproduction and use of the very slowly soluble metaphosphates in whichthe molar ratio of total metal oxide to P205 is 1:1 (the P205accordingly constituting analytically 50 molar per cent of thecomposition), and the tripolyphosphates in which the molar ratio oftotal metal oxide to P205 is 5:3 (the P205 accordingly constitutinganalytically 37 molar per cent of the composition). It will beunderstood, however, that glassy molecularly dehy-: drated phosphates ofcompositions intermediate the metaphosphate and tripolyphosphate may beused according to the present invention. The glassy molecularlydehydrated phosphates having compositions intermediate the metaphosphateand the tripolyphosphate may be made in the same general manner asdescribed for the production of the metaphosphate glass andtripolyphosphate glass except that the molar' ratio of total metal oxideto P205 is between 1:1 and 5:3 (i. e., the P205 constitutes analyticallyfrom 50 molar per cent to 37 molar per cent of the composition). It isdifilcult to makemolecularly dehydrated phosphate glasses with a molarratio of total metal oxide to P205 exceeding that of 5:3 correspondingto the tripolyphosphate composition. From equations 5 and 6 it isevident that in both the sodium-calciumlmetaphosphate and in thesodium-calcium tripolyphosphate, the Na2O constitutes analytically 2 5,molar per centv of the composition. The Ca0 varies from 25 molar percent in the metaphosphate to 37 molar per cent in the tripolyphosphate.The P205 varies from 50. molar per cent in the metaphosphate to 37 molarper cent in the tripolyphosphate.

The term glassy molecularly dehydrated phosphate as used herein isintended to include the glassy metaphosphates having a. ratio of totalmetal oxide to P205 of 1:1, the glassy tripolyphosphates having a molarratio of total metal oxide to P205 of 5:3, and the glassy compositionshaving compositions intermediate the metaphosphate and tripolyphosphatewherein the molar ratio of total metal oxide to P 05 ranges between 1:1and 5 :3. All of these glasses are molecularly dehydrated phosphatessince they may be considered as derived from orthophosphoric acid or thesalts thereof by dehye dration which effects an atomic rearrangementwithin the phosphate molecule.

I claim:

A homogeneous vitreous material as a glassy water-soluble fusion productconsisting analytically of the oxides: NazO, P205 and CaO, the P205being present to the extent of substantially 50 molar per cent of thetotal molar content of said oxides, the CaO and Na20 forming theremainder of said total molar content and each beingpresent to an extentof about 25, molar. per cent of the. total molar content of said oxides.

GEORGE B. HATQEL Refercnces on following page 5 6 4 REFERENCES CITEDNumber Name Date of rd in the 2,358,965 Durgin et a1. Sept. 26, 1944 21; g g gg gfi are 2,365,489 Partridge Dec. 19, 1944 2,370,472 King Feb.2'7, 1945 UNITED STATES PATENTS OTHER REFERENCES Number Name 2 Date295,410 Knafli Mar, 18, 1884 ube fur Anorg. und Allgememe Chenue,1,654,404 Blumenberg D6C.27,1927 v01.230 (1 s123-128. 2,081,613 i b hMay 25, 937 Treadwell et aL: Helv. Ch1m. Acta, v01. 20 2,142,944Kerschbaum Jan. 3, 1939 1 pa e 931. 2,235,955 Williams Mar. 25, 1941 'ESe15 al -I Z- fur Anorg. und Allg'ememe 2,304,850 Rice Dec. 15, 1942hemie, vol. 237, April 1938, page 121.

2,337,856 Rice et a1. Dec. 28, 1943

